1. Technical Field
This invention relates to data recording disk files which have a generally sealed enclosure for the read/write heads and the data recording disks, and in particular to a filter for preventing contaminants from entering the sealed enclosure through the disk file spindle.
2. Description of the Prior Art
Conventional magnetic recording disk files have one or more rotatable data disks which are accessed by read/write heads which are supported on a thin cushion of air between the heads and the rotating disks. The disks are mounted for rotation on a spindle, which includes a rotatable shaft, a bearing assembly supporting the shaft to the disk file frame, and a hub located at the end of the shaft. Because of the extremely low flying height of the heads, particulate matter entering the head/disk area can cause the heads to crash, thereby damaging the heads and disks.
Certain disk files operate as generally sealed enclosure, as contrasted with those disk files which force filtered outside air at a relatively high flow rate through the head/disk area. In these sealed disk files, the rotating disks serve as the air pump to continually recirculate air within the generally sealed enclosure. A make-up filter is required to permit air to enter the sealed enclosure at an extremely low flow rate, since some air does escape from the enclosure during normal operation. Air may also escape the enclosure through the spindle bearings since the pumping action of the disks generates a low-pressure area near the hub at the end of the spindle. The spindle bearings are a primary source of contaminants.
In order to prevent particulate matter from passing the spindle bearings into the head/disk area, conventional types of seals are used. These include ferrofluidic and labyrinth seals. Ferrofluidic seals are costly and difficult to assemble and repair. Labyrinth seals merely provide a flow impedance for air flowing past the bearings and do not filter out small particulate matter.